Tertiary epoch; between these
extremes no single period was passed without leaving its records in some
part of the great east-to-west Tibetan basin. At the base of the whole
succession there lies a series of schists which have been largely
metamorphosed, and on these rest the oldest of the fossiliferous series,
which, on account of their occurring in the region of snow, has been
named the _Haimanta system_. The upper part of the Haimanta system has
been found to contain the characteristic trilobites of the Cambrian
period of Europe. Over this system lie beds which have yielded in
succession Ordovician and Silurian fossils, forming altogether a compact
division which has been distinguished locally as the _Muth system_. Then
follows the so-called _Kanawar system_, which introduces Devonian
conditions, followed by fossils characteristic of the well-known
mountain limestone of Europe.

Then occurs a break in the succession which varies in magnitude in
different localities, but appears to correspond to great changes in the
physical geography which widely affect the Indian region. This break
corresponds roughly to the upper part of the Carboniferous system of
Europe, and has been suggested as a datum line for distinguishing in
India an older group of fossiliferous systems below (formed in an area
that has been distinguished by the name _Dravidian_), from the younger
group above, which has been distinguished by the name _Aryan_.

During the periods that followed this interruption the bed of the great
Eurasian Ocean seems to have subsided persistently though
intermittently. As the various sediments accumulated the exact position
of the shore-line must have changed to some extent to give rise to the
conditions favourable for the formation at one time of limestone, at
another of shale and at other times of sandy deposits. The whole column
of beds, however, seems to have gone on accumulating without any folding
movements, and they are consequently now found lying apparently in
perfect conformity stage upon stage, from those that are Permian in age
at the base, right through the Mesozoic group, till the time when
Tertiary conditions were inaugurated and the earth movements began which
ultimately drove back the ocean and raised the bed, with its accumulated
load of sediments, into the great folds that now form the Himalayan
Range. This great mass of Aryan strata includes an enormous number of
fossil remains, giving probably a more